A human eye is a specialized sensory organ capable of light reception and is able to receive visual images. Aqueous humor (hereinafter referred to as “aqueous”) is a transparent liquid that fills at least the region between the cornea, at the front of the eye, and the lens. Aqueous is continuously secreted by ciliary processes of a ciliary body to the posterior chamber of the eye and the aqueous flows to the anterior chamber by crossing the pupil, so there is a constant flow of aqueous humor from the ciliary body to the anterior chamber of the eye. The aqueous fluid supplies nutrients to the avascular structures of the eye (for example, the cornea and the lens) and maintains intraocular pressure. Pressure within the eye is determined by a balance between the production of aqueous and its exit through canalicular outflow, uveoscleral outflow, or other outflow routes or pathways.
Many open-angle glaucomas are caused by an increase in the resistance to aqueous drainage through the trabecular meshwork and/or Schlemm's canal (e.g., the canalicular outflow pathways). The tissue of the trabecular meshwork normally allows the aqueous to enter Schlemm's canal, which then empties into aqueous collector channels in the posterior wall of Schlemm's canal and then into aqueous veins, which form the episcleral venous system. The uveoscleral outflow pathways can refer to the aqueous leaving the anterior chamber by diffusion through intercellular spaces among ciliary muscle fibers or through a supraciliary and/or suprachoroidal space.
Intraocular implants (for example, shunts or stents) can be implanted within the eye to facilitate the outflow of aqueous, thereby reducing intraocular pressure. Typical methods of implantation require relatively invasive surgical procedures, pose a risk of excessive trauma to the eye, and require excessive handling of the implant. For example, in a typical method of implantation, an incision is made through the sclera or cornea and the implant is inserted into the desired implantation location using forceps or another like manual grasping device. These forceps are configured for holding, and introducing into the eye only one implant at a time. This requires reloading and repositioning of the forceps prior to inserting each implant into the eye. Once the implants are deposited, the grasping device is removed and the incision is sutured closed.
Alternatively, a trocar, scalpel, or similar instrument can be used to pre-form an incision in the eye tissue before passing the implant into such tissue. After the incision is made in the eye tissue, a trocar can be advanced through the incision and then the implant can be delivered over the trocar.
Prior methods and systems for delivering multiple implants within the same eye typically require the delivery instrument to be removed from the eye and reloaded with a second implant. This reloading process increases the time of surgery, increases the risk of infection due to exposure and to excessive handling of the implant, and increases the risk of trauma to the eye due to multiple entries within an incision.